JPS6121557Y2 - - Google Patents
Info
- Publication number
- JPS6121557Y2 JPS6121557Y2 JP5322284U JP5322284U JPS6121557Y2 JP S6121557 Y2 JPS6121557 Y2 JP S6121557Y2 JP 5322284 U JP5322284 U JP 5322284U JP 5322284 U JP5322284 U JP 5322284U JP S6121557 Y2 JPS6121557 Y2 JP S6121557Y2
- Authority
- JP
- Japan
- Prior art keywords
- air
- exhaust
- fuel ratio
- fuel
- secondary air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000446 fuel Substances 0.000 claims description 88
- 239000003054 catalyst Substances 0.000 claims description 32
- 238000011144 upstream manufacturing Methods 0.000 claims description 21
- 238000002485 combustion reaction Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 description 17
- 239000000203 mixture Substances 0.000 description 14
- 238000007254 oxidation reaction Methods 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 12
- 230000003197 catalytic effect Effects 0.000 description 11
- 239000007789 gas Substances 0.000 description 9
- 230000003647 oxidation Effects 0.000 description 9
- 230000001590 oxidative effect Effects 0.000 description 8
- 230000009471 action Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000010792 warming Methods 0.000 description 3
- 238000007865 diluting Methods 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 235000014676 Phragmites communis Nutrition 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Landscapes
- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Description
【考案の詳細な説明】
本考案は内燃機関、特に排気系に三元触媒装置
を付設した機関の空燃比制御装置に関する。[Detailed Description of the Invention] The present invention relates to an air-fuel ratio control device for an internal combustion engine, particularly an engine having a three-way catalyst device attached to the exhaust system.
内燃機関より排気される排気中の有毒三成分、
即ち、炭化水素EC、一酸化炭素COおよび窒素酸
化物NOxを同時に効率よく低減するための手段
として三元触媒装置が知られている。この三元触
媒装置がその三元性（HC、COの酸化とNOxの還
元）を十分に発揮するためには、第１図に示す転
化率特性から明かなように吸入混合気の空燃比を
ほぼ理論空燃比（ガソリン燃料の場合Ａ／Ｆ＝
14.8）に精度よく制御する必要があり、吸入混合
気の理論空燃比より濃あるいは薄の時にはそれぞ
れ排気が還元雰囲気あるいは酸化雰囲気となり、
NOxの還元およびHC、COの酸化の両方を同時に
十分に行えなくなつてしまう。 Three toxic components in the exhaust from internal combustion engines:
That is, a three-way catalyst device is known as a means for efficiently reducing hydrocarbon EC, carbon monoxide CO, and nitrogen oxide NOx at the same time. In order for this three-way catalyst device to fully demonstrate its three-way properties (oxidation of HC and CO and reduction of NOx), it is necessary to adjust the air-fuel ratio of the intake air-fuel mixture, as is clear from the conversion rate characteristics shown in Figure 1. Almost stoichiometric air-fuel ratio (A/F= for gasoline fuel)
14.8), it is necessary to precisely control the air-fuel ratio, and when the intake air-fuel mixture is richer or leaner than the stoichiometric air-fuel ratio, the exhaust becomes a reducing atmosphere or an oxidizing atmosphere, respectively.
Both NOx reduction and HC and CO oxidation cannot be performed sufficiently at the same time.
そこで、この三元触媒の開発に伴い、該三元触
媒を有効に機能させるべく吸入混合気の空燃比を
目標値にフイードバツク制御する空燃比制御シス
テムが提案されている（例えば特開昭49−117838
号公報）。これは、第２図に例示するように、排
気通路１の三元触媒装置２前流に吸入混合気の空
燃比と密接な関係にある排気成分、つまりO2，
HC，CO，CO2，NOx等の濃度を検出して出力す
る排気センサ３を設ける一方、吸気系燃料供給装
置４例えば気化器の燃料通路もしくは空気導入路
（エアブリード通路）（何れも図示省略）に流量制
御用アクチユエータ５を介装し、前記排気センサ
３の検出信号に基づき電子制御装置６を介してア
クチユエータ５を作動させ、燃料供給装置４から
供給される燃料量を直接もしくは間接的に補正
し、空燃比を目標値に収束制御しようとするもの
である。前記アクチユエータ５としては、通常オ
ン（開）オフ（閉）作動型の電磁弁や通路開口面
積を変化するアナログ作動型の電磁弁等が設けら
れている。燃料供給装置４として燃料噴射装置を
用いる場合は燃料通路に設けられた燃料噴射弁が
アクチユエータ５に相当し、この噴射弁による燃
料噴射量をフイードバツク制御する。７は機関本
体である。前記フイードバツク空燃比制御は具体
的には、例えば気化器の場合予め燃料供給装置４
の各種計量ジエツト（図示省略）径等により、ア
クチユエータ５の全開時および全閉時の空燃比を
設定して、制御目標空燃比に対する空燃比の濃化
幅と稀薄幅とを設定する一方、排気センサ３が制
御目標空燃比の吸入混合気が燃焼した後の排気成
分濃度を検出した時の出力値を電子制御装置６の
比較基準値として設定する。かかる設定により、
排気センサ３の出力値が比較基準値よりも上まわ
つたり、下まわつたりした時に電子制御装置６か
らアクチユエータ５に指令信号を送つて作動制御
し、吸入混合気を前記空燃比の濃化幅と稀薄幅の
設定範囲で濃側に移行させたり、稀薄側に移行さ
せて目標値に収束制御させるのである。燃料噴射
装置の場合も略々同様である。 Therefore, along with the development of this three-way catalyst, an air-fuel ratio control system has been proposed that feedback-controls the air-fuel ratio of the intake air-fuel mixture to a target value in order to make the three-way catalyst function effectively (for example, 117838
Publication No.). As illustrated in FIG. 2, this means that exhaust components that are closely related to the air-fuel ratio of the intake air-fuel mixture, that is, O 2 ,
An exhaust sensor 3 that detects and outputs the concentration of HC, CO, CO 2 , NOx, etc. is provided, while an intake system fuel supply device 4 is installed, such as a fuel passage of a carburetor or an air introduction passage (air bleed passage) (all not shown). ) is provided with a flow rate control actuator 5, and the actuator 5 is actuated via the electronic control device 6 based on the detection signal of the exhaust sensor 3, and the amount of fuel supplied from the fuel supply device 4 is controlled directly or indirectly. This is an attempt to correct the air-fuel ratio and control the air-fuel ratio to converge to the target value. As the actuator 5, a solenoid valve of a normal on (open) and off (close) operation type, an analog operation type solenoid valve that changes the passage opening area, etc. are provided. When a fuel injection device is used as the fuel supply device 4, a fuel injection valve provided in a fuel passage corresponds to the actuator 5, and controls the amount of fuel injected by this injection valve in feedback manner. 7 is the engine body. Specifically, for example, in the case of a carburetor, the feedback air-fuel ratio control is performed in advance by controlling the fuel supply device 4.
The air-fuel ratio when the actuator 5 is fully open and fully closed is set using the diameters of various metering jets (not shown), etc., and the rich and lean widths of the air-fuel ratio are set for the control target air-fuel ratio. The output value when the sensor 3 detects the concentration of exhaust components after the intake air-fuel mixture of the control target air-fuel ratio is combusted is set as the comparison reference value of the electronic control device 6. With such settings,
When the output value of the exhaust sensor 3 exceeds or falls below the comparison reference value, the electronic control device 6 sends a command signal to the actuator 5 to control the operation and enrich the intake air-fuel mixture to the air-fuel ratio. It controls convergence to the target value by shifting to the dark side or to the lean side within the setting range of width and lean width. The same applies to fuel injection devices.
ところが、このようなフイードバツク空燃比制
御システムによつて、三元触媒装置２を十分に機
能させるべく、吸入混合気の空燃比が常時理論空
燃比（Ａ／Ｆ＝14.8）に維持されるようにした場
合、三元触媒装置は第１図からも明かなように
NOxおよびCO，HCのそれぞれの最高転化率で機
能なし得るものではないから、機関の最高燃焼温
度が然程高くならず、NOxの生成量が少なくあ
まり問題とならない一方、HC，COが比較的多量
に排出される運転条件、例えば機関のコールドス
タート時、アイドリング時、減速時、低速低負荷
時ではNOxに比してEC，CO対策が不十分と言え
る。まして、このようなアイドリング、減速、低
速、低負荷運転のようにスロツトルバルブ開度が
全閉若しくは小開度状態で吸気量が少ない運転状
態では、当然排出ガス量も小となると共に排気温
が低下し、三元触媒装置の活性が弱まるものであ
り、従つて、このような運転状態が長引いた場合
には、三元触媒装置が低下しその機能が失われて
HC，COを多量に大気へ放出してしまうのみなら
ず、かかる運転状態から他の運転状態に移行した
場合NOxの還元、勿論HC，COの酸化を十分に行
なえなくなつてしまう結果となる。 However, with such a feedback air-fuel ratio control system, the air-fuel ratio of the intake air-fuel mixture is always maintained at the stoichiometric air-fuel ratio (A/F = 14.8) in order to make the three-way catalyst device 2 function sufficiently. In this case, the three-way catalytic converter is
Since it is not possible to function at the maximum conversion rate of NOx, CO, and HC, the maximum combustion temperature of the engine is not very high, and the amount of NOx produced is small and does not pose much of a problem, while HC and CO are relatively low. It can be said that countermeasures for EC and CO are insufficient compared to NOx under operating conditions that produce large amounts of emissions, such as when the engine is cold starting, idling, decelerating, and at low speeds and low loads. Furthermore, in operating conditions such as idling, deceleration, low speed, and low load operation where the throttle valve opening is fully closed or slightly opened and the intake air amount is small, the amount of exhaust gas will naturally be small and the exhaust temperature will be low. This reduces the activity of the three-way catalytic converter. Therefore, if this operating condition continues for a long time, the three-way catalytic converter will deteriorate and lose its function.
Not only will a large amount of HC and CO be released into the atmosphere, but if this operating state is shifted to another operating state, NOx reduction and, of course, HC and CO oxidation cannot be performed sufficiently.
また、特にコールドスタート時には始動性の向
上のため、通常、理論空燃比よりも濃い混合気を
用いるため、機関から排出されるHC，CO量が多
く、また残存酸素量が極めて少ない状態となる。
加えて、三元触媒装置も暖機していないことと相
俟つてこれらHC，COが酸化されないまま大量に
大気へ放出されてしまう。しかも三元触媒装置に
おいてこのようにHC，COの酸化発熱反応が進ま
ないため、三元触媒装置の暖流が遅れ、十分に機
能し得るまで長時間を要し、従つてNOxの還元
反応開始も遅れてしまう不具合があつた。 Additionally, in order to improve startability, especially during cold starts, a mixture that is richer than the stoichiometric air-fuel ratio is usually used, resulting in large amounts of HC and CO being emitted from the engine, and an extremely low amount of residual oxygen.
In addition, this combined with the fact that the three-way catalytic converter is not warmed up results in a large amount of HC and CO being released into the atmosphere without being oxidized. Moreover, because the exothermic oxidation reaction of HC and CO does not proceed in the three-way catalyst, the warm flow of the three-way catalyst is delayed, and it takes a long time for the three-way catalyst to function properly, which also prevents the NOx reduction reaction from starting. There was a problem that caused a delay.
或いは特開昭49−14809号公報に示されている
ように、排気温度を検出して、排気の低温時に排
気センサ前流に二次空気を供給するものもある
が、排温が上昇すると二次空気を小又は零とする
ことがあり、この結果、吸入混合気の空燃比は薄
くなる。薄くなると再び排温が下がり二次空気供
給、空燃比濃化となる。この繰り返しにより空燃
比は例えばアイドリング中であつても濃薄を繰り
返してしまい、機関の作動状態が安定しなくなつ
てしまう不具合を生じる。また、このように濃薄
を繰り返すと排気の性能も安定しない。つまり、
排気温度が上昇、下降を繰り返すので排気の酸化
零囲気を維持することができなくなつてしまう。 Alternatively, as shown in JP-A-49-14809, there is a system that detects the exhaust temperature and supplies secondary air to the front of the exhaust sensor when the exhaust temperature is low, but when the exhaust temperature rises, the secondary air The amount of secondary air may be small or zero, and as a result, the air-fuel ratio of the intake mixture becomes lean. When it becomes thinner, the exhaust temperature decreases again, leading to the supply of secondary air and enrichment of the air-fuel ratio. As a result of this repetition, the air-fuel ratio repeats enrichment and depletion even during idling, resulting in a problem that the operating state of the engine becomes unstable. Furthermore, if the concentration and dilution are repeated in this way, the exhaust performance will not be stable. In other words,
Since the exhaust gas temperature repeatedly rises and falls, it becomes impossible to maintain the zero oxidation atmosphere of the exhaust gas.
本考案はかかる事情に鑑み、NOxの生成量が
少なくあまり問題とならない一方、HC，COが比
較的多量に排出される吸気系絞り弁の小開度（全
閉も含む）運転状態では、三元触媒装置の前流に
設けられた排気センサの前流又は後流に二次空気
を供給し、又は排気センサの前流と後流と導入さ
れる二次空気量を所定割合にして、総合空燃比
（三元触媒装置に至るまでの間に機関に供給され
る全空気量と全燃料量との比）を稀薄化して、排
気を酸化雰囲気の制御することにより、該三元触
媒装置によりHC，COを高転化率の下で除去させ
総合的な排気の清浄化と同時に、HC，COの酸化
発熱反応により三元触媒装置の暖機促進、高温維
持を計るものである。 In view of these circumstances, the present invention has been proposed in such a way that, while the amount of NOx generated is small and does not pose much of a problem, when the intake system throttle valve is operated at a small opening (including fully closed), where a relatively large amount of HC and CO is discharged, By supplying secondary air to the upstream or downstream of the exhaust sensor installed upstream of the main catalyst device, or by setting the amount of secondary air introduced upstream and downstream of the exhaust sensor at a predetermined ratio, By diluting the air-fuel ratio (the ratio of the total amount of air to the total amount of fuel supplied to the engine before reaching the three-way catalytic converter) and controlling the oxidizing atmosphere in the exhaust gas, the three-way catalytic converter This system removes HC and CO at a high conversion rate and provides comprehensive exhaust purification, while at the same time promoting warm-up of the three-way catalyst and maintaining high temperatures through the oxidation exothermic reaction of HC and CO.
以下本考案の２つの実施例を図面と共に詳述す
る。 Two embodiments of the present invention will be described below in detail with reference to the drawings.
即ち、本考案にあつては第３図に例示するよう
に排気通路１に付設した三元触媒装置２の三元性
を十分に発揮させるべく、排気センサ３の検出信
号に基づき電子制御装置６を介して燃料供給装置
４の燃料通路もしくは空気導入路（何れも図示省
略）に介装した流量制御用アクチユエータ５を作
動させ、吸入混合気の空燃比を目標値、例えば理
論空燃比に収束制御するようにしたフイードバツ
ク空燃比制御システムにあつて、機関の最高燃焼
温度が然程高くならず、NOxの生成量が少ない
一方、HC，COの排気量が比較的多い、吸気系絞
り弁の小開度（全閉も含む）運転状態、例えば機
関冷機時、アイドリング時、減速時、減速・低負
荷時等を検出する検出手段１０と、排気センサ３
の前流又は後流に二次空気を供給して総合空燃比
を稀薄化する手段１１とを設け、前記所定の運転
状態の時に検出手段１０の検出信号に基づき二次
空気供給手段１１を作動させて排気を酸化雰囲気
に制御するようにしてある。 That is, in the present invention, in order to fully utilize the three-way catalyst device 2 attached to the exhaust passage 1 as shown in FIG. The flow rate control actuator 5 installed in the fuel passage or air introduction passage (both not shown) of the fuel supply device 4 is operated through the fuel supply device 4, and the air-fuel ratio of the intake air-fuel mixture is controlled to converge to a target value, for example, the stoichiometric air-fuel ratio. In the case of a feedback air-fuel ratio control system that is designed to Detection means 10 for detecting opening (including fully closed) operating conditions, such as engine cold, idling, deceleration, deceleration/low load, etc., and exhaust sensor 3
means 11 for diluting the overall air-fuel ratio by supplying secondary air to the upstream or downstream of the system, and actuating the secondary air supplying means 11 based on the detection signal of the detection means 10 in the predetermined operating state. The exhaust gas is controlled to an oxidizing atmosphere.
前記所定の運転状態の検出手段１０としては、
スロツトル開度センサS1が用いられる。また、二
次空気供給手段としては、例えば機関回転と同期
して回転するエアポンプあるいは排気脈動により
開閉するリード弁（何れも図示省略）により、二
次空気供給通路１２を介して排気センサ３の前流
又は後流の排気通路１に二次空気を供給する二次
空気供給装置１１ａが用いられる。そして、この
二次空気供給通路１２は２系統に分岐１２ａ，１
２ｂさせ、一方の分岐通路１２ａを排気センサ３
前流の排気通路１に、他方の分岐通路１２ｂを排
気センサ３と三元触媒装置２との間の排気通路１
に接続して、二次空気を排気センサ３前流と、該
センサ３と三元触媒装置２との間に分岐して導入
し得るようにしたものである。 The predetermined operating state detection means 10 includes:
A throttle opening sensor S1 is used. Further, as a secondary air supply means, for example, an air pump that rotates in synchronization with the engine rotation or a reed valve that opens and closes due to exhaust pulsation (both not shown) is used to supply air to the exhaust sensor 3 via the secondary air supply passage 12. A secondary air supply device 11a is used which supplies secondary air to the downstream or downstream exhaust passage 1. This secondary air supply passage 12 branches into two systems 12a and 1.
2b, and one branch passage 12a is connected to the exhaust sensor 3.
The other branch passage 12b is connected to the upstream exhaust passage 1 and the other branch passage 12b is connected to the exhaust passage 1 between the exhaust sensor 3 and the three-way catalyst device 2.
, so that secondary air can be branched and introduced upstream of the exhaust sensor 3 and between the sensor 3 and the three-way catalyst device 2.
ここで、第３図に示す実施例は、通路１２ａ，
１２ｂの分岐点に検出手段１０の信号より電子制
御装置６を介して切換作動される分配制御弁とし
ての切換弁１５を介装してあり、例えば、機関
７、三元触媒装置２が冷機状態もしくは十分に暖
機していない状態での始動、アイドリング、減
速、低送・低負荷運転時は、通路１２ａを介して
排気センサ３前流に二次空気を導入し、また、暖
機後におけるアイドリング、減速、低速・低負荷
運転時には通路１２ｂを介して排気センサ３と三
元触媒装置２との間に二次空気を導入し得るよう
にしたもので、このように冷間時と暖機後におけ
る所定の設定運転状態で二次空気の導入を排気セ
ンサ３の前流と後流とに選択的に切換制御でき
る。 Here, in the embodiment shown in FIG. 3, the passage 12a,
A switching valve 15 as a distribution control valve is installed at the branch point of the detection means 10 via the electronic control device 6 based on a signal from the detection means 10. For example, when the engine 7 and the three-way catalyst device 2 are in a cold state, Or, when starting, idling, decelerating, or operating at low feed rate or low load without being sufficiently warmed up, secondary air is introduced into the front stream of the exhaust sensor 3 via the passage 12a. During idling, deceleration, and low-speed/low-load operation, secondary air can be introduced between the exhaust sensor 3 and the three-way catalyst device 2 through the passage 12b. The introduction of secondary air can be controlled to be selectively switched between the upstream side and the downstream side of the exhaust sensor 3 in a later predetermined set operating state.
また、場合によつて前記スロツトル開度センサ
S1に加え機関冷却水温度、機関潤滑油温度、機関
回転数、機関吸入負圧、ベンチユリー負圧等を検
知するセンサS2…Snを選択的に組合さることも
できる。 In addition, in some cases, the throttle opening sensor
In addition to S1 , sensors S2 ...Sn that detect engine cooling water temperature, engine lubricating oil temperature, engine speed, engine intake negative pressure, ventilate negative pressure, etc. can also be selectively combined.
かかる構成により、前記吸気系絞り弁の小開度
運転状態以外の運転状態では、二次空気供給通路
１２の切換弁１５が閉弁して二次空気の導入を遮
断し、排気センサ３の検出作用により電子制御装
置６より流量制御用アクチユエータ５を作動さ
せ、燃料供給装置４から供給される燃料量を直接
もしくは間接的に補正して、吸入混合気の空燃比
を理論空燃比に収束制御する。この結果、三元触
媒装置２前流の総合空燃比も理論空燃比となつ
て、排気が還元雰囲気と酸化雰囲気の略中間の雰
囲気に制御され三元触媒装置２の三元機能を十分
に発揮させる。ところが、機関のコールドスター
ト時、アイドリング時、減速時、低速・低負荷時
等、機関の最高燃焼温度が然程高くならず、
NOx排出量が問題とならない程少ない一方、
HC，COが多く排出される吸気系絞り弁の小開度
運転状態では、前記検出手段１０の検出作用によ
り、該検出手段１０の検出信号に基づき電子制御
装置６を介して切換弁１５を開動させる。 With this configuration, in operating states other than the small opening operating state of the intake system throttle valve, the switching valve 15 of the secondary air supply passage 12 closes to cut off the introduction of secondary air, and the exhaust sensor 3 detects the As a result, the electronic control device 6 operates the flow control actuator 5, directly or indirectly corrects the amount of fuel supplied from the fuel supply device 4, and controls the air-fuel ratio of the intake air-fuel mixture to converge to the stoichiometric air-fuel ratio. . As a result, the overall air-fuel ratio upstream of the three-way catalyst device 2 also becomes the stoichiometric air-fuel ratio, and the exhaust gas is controlled to an atmosphere approximately halfway between a reducing atmosphere and an oxidizing atmosphere, and the three-way function of the three-way catalyst device 2 is fully exerted. let However, when the engine is cold starting, idling, decelerating, or at low speeds and low loads, the maximum combustion temperature of the engine does not rise as high as it should.
While NOx emissions are so low that they do not pose a problem,
When the intake system throttle valve is operating at a small opening where a large amount of HC and CO are discharged, the switching valve 15 is opened via the electronic control device 6 based on the detection signal of the detection means 10 due to the detection action of the detection means 10. let
従つて、三元触媒装置２前流の排気通路１には
所定量の二次空気が導入され、総合空燃比が理論
空燃比よりも稀薄化されて、排気が酸化雰囲気と
なり、三元触媒装置２でHC，COを最高転化率の
下で転化することができるのである。 Therefore, a predetermined amount of secondary air is introduced into the exhaust passage 1 upstream of the three-way catalyst device 2, the total air-fuel ratio is made leaner than the stoichiometric air-fuel ratio, the exhaust gas becomes an oxidizing atmosphere, and the three-way catalyst device 2 can convert HC and CO at the highest conversion rate.
特にコールドスタート時では、二次空気の供給
により三元触媒装置２で専らHC，COの酸化反応
を行わせるので、この酸化発熱反応により触媒の
暖機が促進され、HC，COの処理のみならずNOx
処理を開始する時期も進めることができるのであ
る。しかも、切換弁１５により通路１２ａを介し
て排気センサ３前流に二次空気を供給するため、
該排気センサ３前流でHC，COの酸化が促進され
て排気温度を上昇することができるので、該排気
センサ３の検出作用開始時期、即ちフイードバツ
ク空燃比制御開始時期を進めることができる利点
があり、特に排気センサとしてO2センサを使用
した場合、該O2センサはその表面でHC，COを
酸化反応させて残存O2量を検出して空燃比の
濃、薄を判定するので、このようにHC，COの酸
化がセンサ上流で促進されることと、排気温の上
昇によりO2センサ自体のHC，COの酸化反応が
良好に行われることにより、O2センサの暖機も
早まり残存O2量の真値を速かに検出することが
でき、早期から精度のよいフイードバツク制御を
行わせることができるのである。また、機関暖機
後におけるアイドリング時、減速時、低速・低負
荷時のように、スロツトバルブが全閉若しくは小
開度状態で排気温度が低くかつ排出ガス量が少な
いために三元触媒装置２の温度が下がり活性が弱
まる運転状態にあつても、前述のように二次空気
供給の下でHC，COの酸化反応を活発に行わせる
ため、この反応熱により三元触媒装置２の反応温
度が確保され、優れた浄化機能を持続できるので
ある。また、かかる運転状態では吸入混合気が濃
化されるので機関の安定性もよくなる。暖機後は
二次空気は通路１２ｂを介して排気センサ後流に
導入されるため、排気センサ３の検出作用が二次
空気導入によつて何等影響を受けないため、空燃
比を常時目標値（理論空燃比）にフイードバツク
制御できるので、二次空気導入が遮断された直後
でもただちに引続いて三元触媒装置２の三元性を
十分に発揮させ得る効果がある。 Particularly during a cold start, the supply of secondary air causes the three-way catalyst device 2 to exclusively perform the oxidation reaction of HC and CO, so this oxidation exothermic reaction accelerates the warm-up of the catalyst, allowing it to process only HC and CO. NOx
The timing for starting processing can also be moved forward. Moreover, since the switching valve 15 supplies secondary air to the upstream side of the exhaust sensor 3 via the passage 12a,
Since the oxidation of HC and CO is promoted upstream of the exhaust sensor 3 and the exhaust temperature can be raised, there is an advantage that the timing at which the detection action of the exhaust sensor 3 starts, that is, the timing at which feedback air-fuel ratio control starts can be advanced. In particular, when an O 2 sensor is used as an exhaust sensor, the O 2 sensor oxidizes HC and CO on its surface and detects the amount of remaining O 2 to determine whether the air-fuel ratio is rich or lean. As the oxidation of HC and CO is promoted upstream of the sensor, and the oxidation reaction of HC and CO in the O 2 sensor itself is carried out favorably due to the rise in exhaust temperature, the warm-up of the O 2 sensor is also accelerated and the remaining oxidation is reduced. The true value of the O 2 amount can be detected quickly, and accurate feedback control can be performed from an early stage. In addition, when the slot valve is fully closed or slightly opened, such as when idling after warming up the engine, decelerating, or at low speeds and low loads, the exhaust temperature is low and the amount of exhaust gas is low, so the three-way catalytic device 2 Even in operating conditions where the temperature is low and the activity is weakened, the reaction temperature of the three-way catalyst device 2 is raised by this reaction heat in order to actively carry out the oxidation reaction of HC and CO under the secondary air supply as described above. This ensures that the excellent purification function can be maintained. In addition, under such operating conditions, the intake air-fuel mixture is enriched, which improves the stability of the engine. After warming up, the secondary air is introduced downstream of the exhaust sensor through the passage 12b, so the detection action of the exhaust sensor 3 is not affected in any way by the introduction of the secondary air, so the air-fuel ratio is always kept at the target value. Since feedback control can be performed to the (stoichiometric air-fuel ratio), the ternary nature of the three-way catalytic converter 2 can be fully exerted even immediately after the introduction of secondary air is shut off.
ここで、機関暖機後におけるアイドリング、減
低速・低負荷運転時では二次空気供給量が少ない
場合には正常に機能している排気センサ３の検出
作用により吸入混合気は濃化されるが総合空燃比
は理論空燃比に収束制御され、HC，COを最高転
化率の下で除去できなくなることがあるので、こ
の対策として、二次空気供給通路１２ａに設けた
オリフイス１４ａの径を任意に設定して排気温を
低下させず、しかもフイードバツク制御し切れな
い程度の多量の二次空気が導入されるように、つ
まり、アクチユエータ５の全開作動（導入空気に
よる燃料補正の場合）もしくは全開作動（燃料の
直接制御の場合）により、空燃比が設定幅で濃化
されても、センサ３前流の総合空燃比が理論空燃
比よりも稀薄（酸化雰囲気）となるように設定す
ることが望ましい。 Here, when the secondary air supply amount is small during idling after warming up the engine, reduced speed, and low load operation, the intake air-fuel mixture is enriched due to the detection action of the normally functioning exhaust sensor 3. The total air-fuel ratio is controlled to converge to the stoichiometric air-fuel ratio, and HC and CO may not be removed at the maximum conversion rate.As a countermeasure, the diameter of the orifice 14a provided in the secondary air supply passage 12a may be adjusted arbitrarily. In other words, the actuator 5 is set to fully open operation (in the case of fuel correction using introduced air) or fully open operation ( Even if the air-fuel ratio is enriched within a set range (in the case of direct fuel control), it is desirable to set the overall air-fuel ratio upstream of the sensor 3 to be leaner (oxidizing atmosphere) than the stoichiometric air-fuel ratio.
以上述べたとおり、第３図に示す実施例は、
HC，COの効果的な除去の他、排気センサ３の早
期の活性化によるフイードバツク制御開始時期の
促進、三元触媒装置２の暖機促進、三元触媒装置
２の反応温度の確保並に暖機後における前記設定
運転状態から通常運転に移行した際の三元触媒装
置２の三元性の持続等を実現できるのである。 As mentioned above, the embodiment shown in FIG.
In addition to effective removal of HC and CO, early activation of the exhaust sensor 3 accelerates the start of feedback control, accelerates the warm-up of the three-way catalyst device 2, secures the reaction temperature of the three-way catalyst device 2, and warms up the three-way catalyst device 2. This makes it possible to maintain the ternary nature of the three-way catalytic converter 2 when the setting operation state after the machine shifts to normal operation.
第４図に示す実施例は、通路１２ａ，１２ｂの
分岐点に検出手段１０の信号により電子制御装置
６を介して開動して、両通路１２ａ，１２ｂに所
定分配割合で二次空気を供給する分配制御弁とし
ての分配装置１６を介装したもので、両通路１２
ａ，１２ｂから導入される二次空気量は三元触媒
装置２前流の総合空燃比が理論空燃比よりも稀薄
となつて排気が酸化雰囲気となるように任意の設
定の下で供給するのは前述の実施例の場合と同様
であるが、運転条件により通路１２ａ，１２ｂか
ら排気センサ３前流に供給される二次空気量を任
意に撰定することにより、吸入混合気の空燃比を
適切にフイードバツク制御して当該設定運転状態
にあつても燃費、出力性能を向上させ、なおかつ
総合的な排気対策を実現し得る。 In the embodiment shown in FIG. 4, the branch point of the passages 12a and 12b is opened via the electronic control device 6 in response to a signal from the detection means 10, and secondary air is supplied to both passages 12a and 12b at a predetermined distribution ratio. A distribution device 16 as a distribution control valve is installed, and both passages 12
The amount of secondary air introduced from a and 12b is supplied under arbitrary settings so that the total air-fuel ratio upstream of the three-way catalyst device 2 is leaner than the stoichiometric air-fuel ratio and the exhaust gas becomes an oxidizing atmosphere. is the same as in the previous embodiment, but the air-fuel ratio of the intake air-fuel mixture can be adjusted by arbitrarily selecting the amount of secondary air supplied from the passages 12a and 12b to the upstream side of the exhaust sensor 3 depending on the operating conditions. Through appropriate feedback control, fuel efficiency and output performance can be improved even under the set operating conditions, and comprehensive exhaust countermeasures can be realized.
第３図，４図中１４ａ，１４ｂは分岐通路１２
ａ，１２ｂに介装した計量オリフイスである。 In Figures 3 and 4, 14a and 14b are branch passages 12.
This is a measuring orifice installed in a and 12b.
以上要するに本考案によれば、機関の最高燃焼
温度が然程高くなく、NOx排気量が問題となら
ない程少ない一方、HC，COが比較的多く排出さ
れる排気系絞り弁の小開度運転状態では、排気系
の三元触媒装置の前流に設けられた排気センサの
前流又は後流に二次空気を供給し、又は排気セン
サの前流と後流とに導入される二次空気量を所定
割合にして総合空燃比を稀薄化するので、つまり
排気を酸化雰囲気側に移行させるので三元触媒装
置によりHC，COを最高転化率の下で除去させ
て、三元触媒装置を有効に機能させることにでき
るのであり、しかもかかる運転状態として代表さ
れるコールドスタート時には、三元触媒装置の暖
機促進と、排気温度の上昇促進による排気センサ
の検出作用開始時期の促進によりフイードバツク
空燃比制御並びに三元触媒装置の三元機能を早期
から行わせることができる。またアイドリング、
減速、低速・低負荷運転時が長引くような場合に
あつても三元触媒装置の反応温度を十分に確保さ
せることができ、全運転域に亘つて総合的な排気
対策を実現し得るという多大な効果を有する。更
に本願考案では、吸気系の絞り弁開度を検出し
て、絞り弁の全開（アイドル、減速）、小開度
（低負荷）のときには空燃比は所定の値に濃化さ
れ、濃薄を繰り返すことなく機関の作動状態がき
わめて安定し、拝気を酸化雰囲気に維持すること
ができる効果がある。 In summary, according to the present invention, the maximum combustion temperature of the engine is not very high and the amount of NOx emissions is so low that it does not pose a problem, while the exhaust system throttle valve is operated at a small opening in which relatively large amounts of HC and CO are emitted. In this case, secondary air is supplied to the upstream or downstream of the exhaust sensor installed upstream of the three-way catalyst device in the exhaust system, or the amount of secondary air introduced to the upstream and downstream of the exhaust sensor. Since the total air-fuel ratio is diluted by setting a predetermined ratio of Furthermore, during a cold start, which is typical of such operating conditions, feedback air-fuel ratio control is achieved by accelerating the warm-up of the three-way catalytic converter and accelerating the start of the detection action of the exhaust sensor by accelerating the rise in exhaust temperature. In addition, the three-way function of the three-way catalyst device can be performed from an early stage. Also idling,
Even in cases where deceleration, low speed, and low load operation are prolonged, the reaction temperature of the three-way catalytic converter can be ensured sufficiently, making it possible to realize comprehensive exhaust countermeasures over the entire operating range. It has a great effect. Furthermore, the present invention detects the throttle valve opening of the intake system, and when the throttle valve is fully open (idle, deceleration) or small (low load), the air-fuel ratio is enriched to a predetermined value, and the air-fuel ratio is enriched to a predetermined value. This has the effect of keeping the engine in an extremely stable operating condition without repeating itself, and keeping the air in an oxidizing atmosphere.
第１図はNOx，HC，COの転化率特性を示す説
明図、第２図はフイードバツク空燃比制御システ
ムの略示的説明図、第３図は本考案装置の実施例
の略示的説明図、第４図は他の実施例の略示的説
明図である。
１……排気通路、５……流量制御用アクチユエ
ータ、２……三元触媒装置、３……排気センサ、
４……燃料供給装置、６……電子制御装置、１０
……運転状態検出手段、１１……二次空気供給手
段、１１ａ……二次空気供給装置、１２……二次
空気供給通路、１５……切換弁、１６……分配装
置。
Fig. 1 is an explanatory diagram showing the conversion rate characteristics of NOx, HC, and CO, Fig. 2 is a schematic explanatory diagram of the feedback air-fuel ratio control system, and Fig. 3 is a schematic explanatory diagram of an embodiment of the device of the present invention. , FIG. 4 is a schematic explanatory diagram of another embodiment. 1... Exhaust passage, 5... Actuator for flow rate control, 2... Three-way catalyst device, 3... Exhaust sensor,
4...Fuel supply device, 6...Electronic control device, 10
... Operating state detection means, 11 ... Secondary air supply means, 11a ... Secondary air supply device, 12 ... Secondary air supply passage, 15 ... Switching valve, 16 ... Distribution device.
Claims (1)
いて、吸気系燃料供給装置の燃料通路もしくは空
気導入路に流量制御用アクチユエータを介装する
と共に、排気系の三元触媒装置前流に排気成分濃
度を検出する排気センサを設け、該排気センサの
検出信号に基づき電子制御装置を介して前記アク
チユエータを作動させ、吸入混合気の空燃比を目
標値にフイードバツク制御するように構成する一
方、二次空気供給通路を２系統に分岐して前記排
気センサの前流と後流とに接続し、前記二次空気
供給通路の分岐点に分配制御弁を設けると共に、
機関運転状態検出手段を設け、該手段の出力に応
じて前記分配制御弁を作動させて、前記排気セン
サの前流と後流とへの二次空気分配割合を制御す
ることを特徴とする空燃比制御装置。 In an internal combustion engine equipped with a three-way catalyst device in the exhaust system, a flow control actuator is installed in the fuel passage or air introduction path of the intake system fuel supply device, and the exhaust component concentration is controlled upstream of the three-way catalyst device in the exhaust system. An exhaust sensor for detecting the The supply passage is branched into two systems and connected to the upstream and downstream of the exhaust sensor, and a distribution control valve is provided at the branch point of the secondary air supply passage, and
An engine operating state detecting means is provided, and the distribution control valve is operated according to the output of the means to control the ratio of secondary air distribution to the upstream and downstream of the exhaust sensor. Fuel ratio control device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5322284U JPS59177756U (en) | 1984-04-11 | 1984-04-11 | Air fuel ratio control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5322284U JPS59177756U (en) | 1984-04-11 | 1984-04-11 | Air fuel ratio control device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59177756U JPS59177756U (en) | 1984-11-28 |
| JPS6121557Y2 true JPS6121557Y2 (en) | 1986-06-27 |
Family
ID=30183570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5322284U Granted JPS59177756U (en) | 1984-04-11 | 1984-04-11 | Air fuel ratio control device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59177756U (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009156222A (en) * | 2007-12-27 | 2009-07-16 | Yamaha Motor Co Ltd | Secondary air supply system and vehicle |
-
1984
- 1984-04-11 JP JP5322284U patent/JPS59177756U/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59177756U (en) | 1984-11-28 |
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